My HomePod is currently linked to a spare iPhone 5s that is signed into a dummy iCloud account so that I can use features like reminders, etc. without having my messages accessible to everyone in the house. Plus, the phone never leaves the house so those features always work. So far no problem updating HomePod as iOS 12 works on iPhone 5s. My question is - does the linked device have to be running the latest version of iOS for the HomePod to be able to update to its latest version? In other words, will I be able to continue using the iPhone 5s as the linked device and still update the HomePod later this year to its version of iOS 13, even if the iPhone itself cannot run iOS 13? I've read a lot of stuff and this is still not clear to me.